linux-kernel - Re: [PATCH v3 1/6] media: rc: update sunxi-ir driver to get base clock frequency from devicetree

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Message-ID: <20180105154347.3awwaarvicbyvmnf@gofer.mess.org>
Date:   Fri, 5 Jan 2018 15:43:47 +0000
From:   Sean Young <sean@...s.org>
To:     Philipp Rossak <embed3d@...il.com>
Cc:     mchehab@...nel.org, robh+dt@...nel.org, mark.rutland@....com,
        maxime.ripard@...e-electrons.com, wens@...e.org,
        linux@...linux.org.uk, p.zabel@...gutronix.de,
        andi.shyti@...sung.com, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v3 1/6] media: rc: update sunxi-ir driver to get base
 clock frequency from devicetree

On Tue, Dec 19, 2017 at 09:07:42AM +0100, Philipp Rossak wrote:
> This patch updates the sunxi-ir driver to set the base clock frequency from
> devicetree.
> 
> This is necessary since there are different ir receivers on the
> market, that operate with different frequencies. So this value could be
> set if the attached ir receiver needs a different base clock frequency,
> than the default 8 MHz.
> 
> Signed-off-by: Philipp Rossak <embed3d@...il.com>

Acked-by: Sean Young <sean@...s.org>


Sean

> ---
>  drivers/media/rc/sunxi-cir.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/rc/sunxi-cir.c b/drivers/media/rc/sunxi-cir.c
> index 97f367b446c4..f500cea228a9 100644
> --- a/drivers/media/rc/sunxi-cir.c
> +++ b/drivers/media/rc/sunxi-cir.c
> @@ -72,12 +72,8 @@
>  /* CIR_REG register idle threshold */
>  #define REG_CIR_ITHR(val)    (((val) << 8) & (GENMASK(15, 8)))
>  
> -/* Required frequency for IR0 or IR1 clock in CIR mode */
> +/* Required frequency for IR0 or IR1 clock in CIR mode (default) */
>  #define SUNXI_IR_BASE_CLK     8000000
> -/* Frequency after IR internal divider  */
> -#define SUNXI_IR_CLK          (SUNXI_IR_BASE_CLK / 64)
> -/* Sample period in ns */
> -#define SUNXI_IR_SAMPLE       (1000000000ul / SUNXI_IR_CLK)
>  /* Noise threshold in samples  */
>  #define SUNXI_IR_RXNOISE      1
>  /* Idle Threshold in samples */
> @@ -122,7 +118,8 @@ static irqreturn_t sunxi_ir_irq(int irqno, void *dev_id)
>  			/* for each bit in fifo */
>  			dt = readb(ir->base + SUNXI_IR_RXFIFO_REG);
>  			rawir.pulse = (dt & 0x80) != 0;
> -			rawir.duration = ((dt & 0x7f) + 1) * SUNXI_IR_SAMPLE;
> +			rawir.duration = ((dt & 0x7f) + 1) *
> +					 ir->rc->rx_resolution;
>  			ir_raw_event_store_with_filter(ir->rc, &rawir);
>  		}
>  	}
> @@ -148,6 +145,7 @@ static int sunxi_ir_probe(struct platform_device *pdev)
>  	struct device_node *dn = dev->of_node;
>  	struct resource *res;
>  	struct sunxi_ir *ir;
> +	u32 b_clk_freq = SUNXI_IR_BASE_CLK;
>  
>  	ir = devm_kzalloc(dev, sizeof(struct sunxi_ir), GFP_KERNEL);
>  	if (!ir)
> @@ -172,6 +170,9 @@ static int sunxi_ir_probe(struct platform_device *pdev)
>  		return PTR_ERR(ir->clk);
>  	}
>  
> +	/* Base clock frequency (optional) */
> +	of_property_read_u32(dn, "clock-frequency", &b_clk_freq);
> +
>  	/* Reset (optional) */
>  	ir->rst = devm_reset_control_get_optional_exclusive(dev, NULL);
>  	if (IS_ERR(ir->rst))
> @@ -180,11 +181,12 @@ static int sunxi_ir_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = clk_set_rate(ir->clk, SUNXI_IR_BASE_CLK);
> +	ret = clk_set_rate(ir->clk, b_clk_freq);
>  	if (ret) {
>  		dev_err(dev, "set ir base clock failed!\n");
>  		goto exit_reset_assert;
>  	}
> +	dev_dbg(dev, "set base clock frequency to %d Hz.\n", b_clk_freq);
>  
>  	if (clk_prepare_enable(ir->apb_clk)) {
>  		dev_err(dev, "try to enable apb_ir_clk failed\n");
> @@ -225,7 +227,8 @@ static int sunxi_ir_probe(struct platform_device *pdev)
>  	ir->rc->map_name = ir->map_name ?: RC_MAP_EMPTY;
>  	ir->rc->dev.parent = dev;
>  	ir->rc->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
> -	ir->rc->rx_resolution = SUNXI_IR_SAMPLE;
> +	/* Frequency after IR internal divider with sample period in ns */
> +	ir->rc->rx_resolution = (1000000000ul / (b_clk_freq / 64));
>  	ir->rc->timeout = MS_TO_NS(SUNXI_IR_TIMEOUT);
>  	ir->rc->driver_name = SUNXI_IR_DEV;
>  
> -- 
> 2.11.0